This invention relates to an apparatus for two-sided printing. More particularly, this invention relates to a desk-top laser printer responsive to computer generated signals for printing a document on two sides.
At the present time, thousands of banks, brokerage houses and other financial institutions are printing millions of weekly, bi-weekly and monthly statements on one side of pre-printed statement forms. For the most part, these statements are printed off of mainframe or large-scale mini-computers. Affordable printers capable of handling mainframe and mini-computer output are either chain or dot-matrix printers. Consequently, printing both sides of paper having the conventional quality would masticate the paper.
Conventional two-sided photocopying and book printing present problems which have perhaps inhibited efforts to develop two-sided printing of financial type statements. Such problems include a warping of the paper which results from the high levels of heat employed. More moisture flees from the side of the paper in contact with the heated elements than from the more remote side of the paper. In addition, the deposition of electrostatic charges causes the paper sheets to cling to one another and to other surfaces. Both the warping of the paper sheets and the deposited electrostatic charge cause paper jams in the machinery. Avoiding or clearing the paper jams requires personnel to be present to monitor and correct problems as they occur. Sometimes, papers printed on one side are placed aside for flattening prior to printing on the opposite side. Such efforts increase costs and delay the production of the desired documents.
An object of the present invention is provide a printing system or apparatus for printing two-sided documents in response to computer-generated signals encoding the documents.
Another object of the present invention is to provide such a system or apparatus which can handle mainframe and other large-scale computer output.
A further object of the present invention is to provide such a system or apparatus which prints on each side of a sheet of paper in real time.
Yet another object of the present invention is to provide such a system or apparatus which can utilize laser printer technology and basic or conventional printer driver programming.
An additional object of the present invention is to provide such a system or apparatus which is simple to manufacture, assemble and implement.
These and other objects of the present invention will be apparent from the descriptions and drawings hereof
A printing apparatus comprises, in accordance with the present invention, a desk-top printer housing having a paper input port, a paper output port and a data input port. A digital processor is disposed in the housing and is operatively connected to the data input port. The processor is programmed to detect odd pages and even pages in an electronically encoded document arriving via the data input port and to separate odd pages of the document from even pages thereof. A paper moving engine including rollers is disposed in the housing for moving a paper sheet through the printer housing from the paper input port to the paper output port along a predetermined path. A first laser printing assembly is disposed in the housing along one side of the path for printing an odd-numbered page of the document along one side of the paper sheet. A second laser printing assembly is disposed in the housing along an opposite side of the path for printing an even-numbered page of the document along an opposite side of the paper sheet. The processor is operatively connected to the laser printing assemblies for controlling the first laser printing assembly to print the odd-numbered page of the document along the one side of the paper sheet and for controlling the second laser printing assembly to print the even-numbered page of the document along the opposite side of the paper sheet.
Preferably, the paper path is essentially linear. One of the laser printing assemblies is located above the path while the other laser printing assembly is located below the path.
Because the paper travels along a linear or straight path from one laser printing assembly to the other, the paper is easily aligned. There is less paper jamming and less paper warping than there would be in a printer with a curved paper path between the two laser print stations.
Because the laser print stations can be located essentially right next to one another, there is no need to provide the processor with multiple buffers for temporarily storing several pages. At most, a single output buffer is necessary to store one side of a page while the other side is being printed. Conventional RAM is sufficient to implement the output buffer.
It is to be noted that the laser printing assemblies are essentially identical to laser printing assemblies in conventional desk-top laser printers. Each laser printing assembly includes, for example, a drum having a photosensitive surface, a toner reservoir, a laser, a toner waste reservoir, an erase lamp, and a corona wire.
It is preferable that one laser printing assembly is located below the paper path while the other laser printing assembly is located in a more conventional position above the paper path. The laser printing assembly located above the paper path is essentially identical to existing laser printing assemblies. Moreover, only minor modifications are necessary to adapt a conventional laser printing assembly for disposition below the paper path. Generally, this second laser printing assembly is in an upside down configuration, with alterations in structure necessary to accommodate that inverted arrangement being made.
In accordance with a feature of the present invention, the two laser printing assemblies are mounted to a carriage which is movably disposed in the housing. Thus, the laser printing assemblies may be easily removed from the housing for servicing. One of the laser printing assemblies may be mounted to an upper side of the carriage, while the other laser printing assembly is mounted to an underside of the carriage. Accordingly, a toner cartridge of the one laser printing assembly is removed from above the carriage whereas a toner cartridge of the other laser printing assembly is removed from below the carriage.
Generally, it is contemplated that the laser printer apparatus has only one engine for moving the paper. The one engine is coupled to a sufficient number of rollers placed in appropriate locations to move the paper along the linear path past the first print station and subsequently the second print station and out the paper output port.
The processor is programmed to synchronize operation of the first laser printing assembly and the second laser printing assembly so that opposite sides of essentially every sheet bear consecutive pages. The processor is further programmed to generate the document from (1) encoded information peculiar to the document and (2) standard textual and graphic information incorporated into a plurality of documents.
A printing method in accordance with the present invention utilizes a desk-top laser printer for printing documents encoded in computer generated digital signals, the laser printer having two laser printing assemblies disposed in a single desk-top housing, the laser printer including a digital processor which is disposed in the housing and is operatively coupled to the printing assemblies. Pursuant to the inventive method, a multiple page document in digitally encoded form is transmitted to the processor via a data input of the laser printer. The processor is operated to detect odd pages and even pages in the document and to separate odd pages of the document from even pages thereof. A paper sheet is moved through the housing from a paper input port to a paper output port along a predetermined path, the printing assemblies being disposed along opposite sides of the path. One of the printing assemblies is energized, in response to a signal from the processor, to print an odd-numbered page of the document along one side of the paper sheet, while the other of the printing assemblies is energized, in response to another signal from the processor, to print an even-numbered page of the document along an opposite side of the paper sheet.
Where the laser printing assemblies are mounted to a carriage movably disposed in the housing, the method further comprises moving the carriage and the printing assemblies at least partially out of the housing for equipment servicing purposes. Where one of the printing assemblies is mounted to an upper side of the carriage and the other printing assembly is mounted to an underside of the carriage, the method also comprises removing a toner cartridge of the one of the laser printing assemblies from above the carriage and a toner cartridge of the other of the laser printing assemblies from below the carriage.
In accordance with another feature of the present invention, the processor is operated to control energization of the laser printing assemblies so that opposite sides of essentially every sheet sent through the laser printer portion bear consecutive pages.
The processor is operated to synchronize operation of the laser printing assemblies so that opposite sides of essentially every sheet sent through the laser printer bear consecutive pages. The processor is additionally operated to generate the document from (1) encoded information peculiar to the document and (2) standard textual and graphic information incorporated into a plurality of documents.
A printing system or assembly in accordance with the present invention is a high-volume printing system which can print customer data, e.g., on financial statements, in real time, using black and white laser printing technology and basic or conventional printer driver programming.
A printing system or assembly in accordance with the present invention reduces the number of sheets of paper necessary to print financial statements by 50% or more, concomitantly reducing printing and mailing costs. In addition, the system eliminates the need to use expensive pre-printed paper stock for financial statements. Logos may be printed on the front of each sheet in real time, while legal compliance information is printed only on the last face of a statement. The quality of the printed characters may be significantly improved over conventional methods of statement printing, up to the highest laser standards. Moreover, development costs can be substantially decreased through the utilization of existing (off-the-shelf) laser printer engines (preferably using powerful RISC processors).
A printing system or assembly for printing two-sided documents in accordance with the present invention can handle mainframe and other large-scale computer output. The printing occurs without essential delay (in real time) in response to computer generated signals. In contrast, in photocopying and other printing methods, there is a substantial delay between printing of one side and printing of the opposing side.
A system or assembly in accordance with the present invention utilizes laser printer technology and basic or conventional printer driver programming.
A laser printer for two-sided laser printing in accordance with the present invention does not require any memory space over and above that normally present in desk-top printers. The conventional RAM space is sufficient for the storage requirements of the present laser printer.
A laser printer for two-sided laser printing in accordance with the present invention is not size or speed sensitive and can be used in a wide range of printer powers and sizes. The two-sided laser printer is easy to maintain and repair. Paper handling is minimized. Accordingly, paper jamming and alignment problems are reduced.
A laser printer for two-sided laser printing in accordance with the present invention is useful for myriad applications, not just high-speed high-volume financial statements.